Effect of microstructure on short fatigue crack growth of wire arc additive manufactured Ti-6Al-4V

Abstract

In the present paper, the short fatigue crack behavior in wire arc additive manufactured (WAAMed) Ti-6Al-4V was investigated. It was found that the crack in the colony microstructure showed the highest fluctuation range (213 μm) because the crack deflected at the colony boundary. While the crack in the duplex microstructure showed the lowest fluctuation range (48.3 μm) because the crack cut through the αp (primary α) and αs (secondary α) directly. In addition, the short crack growth behavior was determined by the highest Schmid factor (M) and the burgers orientation relationship (BOR), which indicated that the short crack tended to pass through the α/β interface along with the basal slip systems within the shortest path distance. It was suggested that the short crack behavior with colony microstructure was determined by the α/β interface while the crack growth behavior with duplex microstructure was determined by the critical resolved stress (τCRSS) and the αs/β interface.